Deciding on the nutrients required in swine diets is the first step in developing a sound feeding program. The next step is deciding what ingredients to combine to meet the nutrient requirements. Table 3 contains the nutrient content of feed ingredients commonly used in swine diets. Table 4 contains the maximum limits for some ingredients. Normal feed ingredients for swine diets include grains, high protein feedstuffs, mineral sources, and several miscellaneous ingredients.
Grains provide most of the energy in a swine diet. Traditionally, the energy content of a grain determined its value. Corn is the standard grain. The requirements in Table 1 and Table 2 are based on diets containing corn. However, other grains can be part of an economical feeding program.
Corn is an excellent source of energy, but it also supplies up to 50 percent of the protein and 30 percent of the lysine in swine diets. Corn contains low levels of calcium and trace minerals, but it can provide 40 percent of the total phosphorus in swine diets. This figure can be misleading, however. Phytic acid binds two-thirds or more of the phosphorus from plant sources. As little as 20 percent of this phosphorus is available for use by the pig.
Wheat, grain sorghum, and some varieties of triticale can replace corn with little or no effect on swine performance. Wheat is equal to corn in energy and contains more protein and lysine than corn. Bird-resistant grain sorghum contains 85 to 95 percent of the energy found in corn. Non-bird-resistant varieties contain 95 to 100 percent of the energy in corn. Both contain higher levels of protein, but slightly lower levels of lysine.
Triticale contains 98 to 100 percent of the energy in corn, and has almost twice the level of lysine found in corn. Properly formulated swine diets with wheat or triticale as the only grain will be similar to corn-based diets in energy content, but they will contain less of the protein source used (usually soybean meal). Corn can be replaced with grain sorghum pound for pound, but the diet will have slightly less energy and lysine.
Barley, oats, and rye can also be included in swine diets, but the energy content of the diet will be lower. Barley contains 85 percent of the energy in corn, oats 80 percent, and rye 82 percent. All contain higher levels of protein and lysine. The lower energy content in each limits its use in swine feeds.
Oats and barley can be used as the only grain if a high-energy ingredient such as fat is added. Rye can make up only 20 percent of swine diets because of poor palatability. Adding higher levels of rye may reduce feed intake and gains. During periods of cold weather, finishing hogs may benefit from barley in the diet. Adding a moderately high-fiber ingredient such as barley (7 percent fiber) may increase the heat produced by these pigs, reducing the heat required during cold weather.
Grain by-products from the milling industry, bakeries, and distilleries can also be used in swine feeds. These products generally contain higher levels of protein and lysine, but they contain only 60 to 80 percent of the energy found in the whole grains. The economics of using these ingredients must be evaluated before including them in swine diets.
While corn is the standard source of energy for swine, soybean meal is the typical protein source for swine diets. The amino acid content of soybean meal complements that of corn. Corn is low in lysine and tryptophan: soybean meal contains high levels of each. The availability of the amino acids in soybean meal is high (pigs can use most of each amino acid). When the price of soybean meal is high, alternate sources of protein are sought.
Other plant products can be used as protein sources for swine diets, but pig performance will generally decrease. Cottonseed meal is a popular protein source for cattle, but low lysine and toxins limit its use in swine diets. Cottonseed meal contains gossypol, which is toxic to swine. Gossypol binds both lysine and iron, making them unavailable to swine. Peanut meal contains more protein than soybean meal, but less lysine. Cottonseed meal and peanut meal should replace no more than half the lysine from soybean meal in swine diets.
Soybeans can provide an excellent source of both energy and lysine, but they contain several compounds that reduce pig performance. Heating (roasting or extruding) soybeans for 3 to 5 minutes to an exit temperature of 245°F (240° to 260°F is acceptable) is adequate to destroy these compounds. Cooked soybeans contain more energy than soybean meal because of their higher fat content. Properly heated soybeans can be an excellent alternative to soybean meal if the price is right.
Animal protein products were once the primary protein source for swine. This was due as much to their high levels of other nutrients (minerals, vitamins) as it was to their high protein content. Meat and bone meal is still used in many swine diets because of its high phosphorus content. Unlike phosphorus from plant sources, the phosphorus in meat and bone meal is readily used by swine.
The main problem with animal by-products is product variation. The level and availability of amino acids can vary greatly between batches from the same processor. This variation can lead to trouble for the producer or small feedmill using small amounts of animal by-products.
High levels of blood meal and possibly tankage may reduce feed intake in pigs. Addition of some blood meal may improve the balance of amino acids in swine diets, but with little improvement in pig performance.
Some animal protein products are often used in diets for weaned pigs. Menhaden fish meal is an excellent source of protein acids for pigs. Young pigs prefer diets containing some fish meal over those containing corn and soybean meal. The high cost limits its use in most other swine diets. Dried skim milk is also an excellent source of amino acids for young pigs. Most milk replacers and diets for early weaned pigs contain high levels of dried skim milk. It provides both energy and amino acids easily digested by the young pig. The cost also limits its use in other swine diets.
Porcine plasma protein is a new ingredient for swine diets. It is expensive, but it is used in very small amounts for young pigs. Early research shows improvements in feed intake and performance in young pigs that are fed this form of protein.
Most ingredients commonly used in swine diets are plant products and poor sources of minerals. As mentioned earlier, some animal products are excellent sources of minerals. Table 5 contains a list of inorganic mineral sources available for swine diets.
Several common feed ingredients do not fit any of the above groups, but are still important. Whey is a by-product from milk processing used in diets for young pigs. Dried whole whey contains over 60 percent lactose (milk sugar). Lactose is an excellent source of energy for pigs after weaning. It also contains high levels of sodium. Salt should be reduced to 0.25 percent of the diet when whey is used.
Fat is often used to increase the energy content of swine feed. Animal
fat is available to many Alabama swine producers. It contains more than
twice as much energy as corn, and it is commonly used in diets for lactating
sows and growing/finishing pigs. Research has shown improvements in pig
and sow performance from adding 3 to 5 percent fat in the diet.